Add runtime schemarouter reconfiguration

The schemarouter now also uses versioned configurations implemented by
shared pointers to configuration objects. Moved all the configuration
management into the Config class. Removed router options from
schemarouter.

server/modules/routing/schemarouter/schemaroutersession.hh

@@ -153,7 +153,7 @@ private:
     DCB*                   m_client;         /**< The client DCB */
     MYSQL_session*         m_mysql_session;  /**< Session client data (username, password, SHA1). */
     SSRBackendList         m_backends;       /**< Backend references */
-    Config*                m_config;         /**< Pointer to router config */
+    SConfig                m_config;         /**< Session specific configuration */
     SchemaRouter*          m_router;         /**< The router instance */
     Shard                  m_shard;          /**< Database to server mapping */
     std::string            m_connect_db;     /**< Database the user was trying to connect to */